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Polio; Infantile paralysis; Post-polio syndrome
Poliomyelitis is a viral disease that can affect nerves and can lead to partial or full paralysis.
Poliomyelitis is a disease caused by infection with the poliovirus. The virus spreads by direct person-to-person contact, by contact with infected mucus or phlegm from the nose or mouth, or by contact with infected feces.
The virus enters through the mouth and nose, multiplies in the throat and intestinal tract, and then is absorbed and spread through the blood and lymph system. The time from being infected with the virus to developing symptoms of disease (incubation) ranges from 5 - 35 days (average 7 - 14 days).
In areas where there is an outbreak, those most likely to get the disease include children, pregnant women, and the elderly. The disease is more common in the summer and fall.
Between 1840 and the 1950s, polio was a worldwide epidemic. Since the development of polio vaccines, the incidence of the disease has been greatly reduced. Polio has been wiped out in a number of countries. There have been very few cases of polio in the Western hemisphere since the late 1970s. Children in the United States are now routinely vaccinated against the disease.
Outbreaks still occur in the developed world, usually in groups of people who have not been vaccinated. Polio often occurs after someone travels to a region where the disease is common. Thanks to a massive, global, vaccination campaign over the past 20 years, polio exists only in a few countries in Africa and Asia.
There are three basic patterns of polio infection: subclinical infections, nonparalytic, and paralytic. Approximately 95% of infections are subclinical infections, which may not have symptoms.
People with subclinical polio infection might not have symptoms, or their symptoms may last 72 hours or less.
Clinical poliomyelitis affects the central nervous system (brain and spinal cord), and is divided into nonparalytic and paralytic forms. It may occur after recovery from a subclinical infection.
Symptoms usually last 1 - 2 weeks.
The health care provider may find signs of meningeal irritation (similar to meningitis), such as stiff neck or back stiffness with difficulty bending the neck. The person also might have difficulty lifting the head or lifting the legs when lying flat on the back, and their reflexes might be abnormal.
The goal of treatment is to control symptoms while the infection runs its course.
People with severe cases may need lifesaving measures, especially breathing help.
Symptoms are treated based on how severe they are. Treatments include:
What to expect depends on the form of the disease (subclinical, nonparalytic, or paralytic) and the site affected. If the spinal cord and brain are not involved, which is the case more than 90% of the time, complete recovery is likely.
Brain or spinal cord involvement is a medical emergency that may result in paralysis or death (usually from respiratory difficulties).
Disability is more common than death. Infection high in the spinal cord or in the brain increases the risk of breathing problems.
Post-polio syndrome is a complication that develops in some patients, usually 30 or more years after their initial infection. Weakness may get worse in muscles that were previously weakened. Weakness may also develop in muscles that previously were thought not to be affected.
Call your health care provider if:
Polio immunization (vaccine) effectively prevents poliomyelitis in most people (immunization is over 90% effective).
Nath A, Berger JR. Poliomyelitis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier. 2007: chap 440.
Silver JK. Post-poliomyelitis syndrome. In: Frontera WR, Silver JK, Rizzo Jr TD, eds. Essentials of Physical Medicine and Rehabilitation. 2nd ed. Philadelphia, Pa: Saunders Elsevier; 2008: chap 137.
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